The Prophet ﷺ forbade a man who was sitting in prayer leaning on his left hand, saying, "This is the prayer of the Jews."
أن النبي ﷺ نهى رجلا وهو جالس معتمدا على يده اليسرى في الصلاة، فقال: إنها صلاة اليهود.
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Hakim (1/272) narrated it via the route of Hisham bin Yusuf, from Maamar, from Ismail bin Umaya, from Nafi, from Ibn Umar, mentioning it as related. Hakim said, "Sahih according to the standard of the two Shaykhs, though they did not include it." Bayhaqi (2/136) also narrated it likewise through his route.Abdul-Razzaq followed him in narrating from Maamar, and from him Imam Ahmad narrated it (6347), and from Ahmad, Abu Dawud narrated it (992), with the wording, "The Messenger of Allah ﷺ forbade a man from sitting during prayer while leaning on his hands." This is the sahih version of the hadith of Abdul-Razzaq as narrated by Ahmad. Those who placed this hadith in the context of leaning while rising from sujud erred, as occurs in Sunan Abu Dawud on the authority of Ahmad bin Muhammad bin Shabuya, Muhammad bin Rafi, and Muhammad bin Abdul-Malik Ghazzal, all narrating from Abdul-Razzaq. Bayhaqi said, "What the narration of Ahmad bin Hanbal indicates is what is meant by the hadith."Then Abu Dawud (994) narrated, through several routes, from Hisham bin Saad, from Nafi, from Ibn Umar, that he saw a man leaning on his left hand while sitting in prayer. In another version, "collapsed onto his left side. He said, 'Do not sit like this, for this is how those who are punished sit.'" This is strong evidence that what is meant by the hadith of Ibn Umar is the disliked form of iqaa.Imam Ahmad (13437), Bazzar in Kashf Astar (549), and Bayhaqi (2/120) all narrated, through the route of Yahya bin Ishaq Silhini, who said, Hammad bin Salama informed me, from Qatada, from Anas bin Malik, that the Messenger of Allah ﷺ forbade iqaa and tawarruk in prayer.Abdullah bin Imam Ahmad said, "My father had abandoned this hadith." Bazzar said, "It is not narrated from Anas except through this route, and I think Yahya erred in it." Bayhaqi said, "Yahya bin Ishaq Silhini alone narrated it from Hammad bin Salama."I say, it is as they said, because it has been established from the Prophet ﷺ that he used to sit in the tawarruk position during his prayer, and it has been established that he forbade iqaa in prayer. So perhaps Yahya bin Ishaq did not preserve the hadith accurately and added "tawarruk" into the hadith about the prohibition of iqaa. And Allah, the Exalted, knows best.